qemuProcessStartManagedPRDaemon: Don't pass -f pidfile to the daemon

Now, that our virCommandSetPidFile() is more intelligent we don't
need to rely on the daemon to create and lock the pidfile and use
virCommandSetPidFile() at the same time.

NOTE that as advertised in the previous commit, this was
temporarily broken, because both virCommand and
qemuProcessStartManagedPRDaemon() would try to lock the pidfile.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>

src/qemu/qemu_process.c

@@ -2850,7 +2850,6 @@ qemuProcessStartManagedPRDaemon(virDomainObjPtr vm)
     g_autoptr(virQEMUDriverConfig) cfg = NULL;
     int errfd = -1;
     g_autofree char *pidfile = NULL;
-    int pidfd = -1;
     g_autofree char *socketPath = NULL;
     pid_t cpid = -1;
     g_autoptr(virCommand) cmd = NULL;
@@ -2869,10 +2868,6 @@ qemuProcessStartManagedPRDaemon(virDomainObjPtr vm)
     if (!(pidfile = qemuProcessBuildPRHelperPidfilePath(vm)))
         goto cleanup;
 
-    /* Just try to acquire. Dummy pid will be replaced later */
-    if ((pidfd = virPidFileAcquirePath(pidfile, false, -1)) < 0)
-        goto cleanup;
-
     if (!(socketPath = qemuDomainGetManagedPRSocketPath(priv)))
         goto cleanup;
 
@@ -2887,13 +2882,10 @@ qemuProcessStartManagedPRDaemon(virDomainObjPtr vm)
 
     if (!(cmd = virCommandNewArgList(cfg->prHelperName,
                                      "-k", socketPath,
-                                     "-f", pidfile,
                                      NULL)))
         goto cleanup;
 
     virCommandDaemonize(cmd);
-    /* We want our virCommand to write child PID into the pidfile
-     * so that we can read it even before exec(). */
     virCommandSetPidFile(cmd, pidfile);
     virCommandSetErrorFD(cmd, &errfd);
 
@@ -2956,7 +2948,6 @@ qemuProcessStartManagedPRDaemon(virDomainObjPtr vm)
         if (pidfile)
             unlink(pidfile);
     }
-    VIR_FORCE_CLOSE(pidfd);
     VIR_FORCE_CLOSE(errfd);
     return ret;
 }